540 C. SOHUCHERT SILURIAN FORMATIONS 



Part II 



THE SILURIAN SECTIONS 



Bondout. New York. — See G. Van Ingen and P. E. Clark: Report of 

 the New York State Paleontologist for 1902-1903, pages 1176-1227. 



Devonian. 



Hudson River contact (see figure 1). The contact between the Cobleskill 

 and the Hudson River thin-bedded sandstones and shales is a 

 markedly unconformable one. The former stands nearly vertical, 

 while the Hudson River series dips northeast by east 48°. The two 

 formations are of very different materials — the Cobleskill is a crystal- 

 line crinoidal limestone with many fossils — and even though the Hud- 

 son River is largely a sandstone series, yet there is no sand or con- 



Pre-Meridian limestone, Mutinal slate, 



dip 80° N. 40° W. dip 60° N. 70° E. 



Figure 1. — Contact oetiveen the Lower Devonian Waterlimes (Cooleskttl) and the Hudson 

 River thin-oedded Sandstones 



Cement quarries at Rondout, New York. After H. D. Rogers, 1859. 



glomeratic material in the adjacent waterlime and but little sand 

 along the contact between the two formations. Though mountains 

 were thrown up here toward the close of the Ordovician (Taconic 

 Disturbance) , they had been reduced to a peneplain before the close 

 of the Silurian, when the seas of Lower Devonian time again invaded 

 the area. 



Binnewater-High Falls, New York. — Eight miles southwest of Eon- 

 dout. See T. C. Brown: American Journal of Science (4), volume 37, 

 1914, pages 464-474. 



Devonian. Helderbergian series. Along the Wallkill Valley Railroad between 

 Binnewater and Rosendale the Helderbergian is exposed in steep 

 cliffs with the strata deformed and sheared. The lowest members are 

 seen in the first cut north of Binnewater station and about the cement 

 mill here. In the basal 4 inches of the Cobleskill impure knobbly and 

 cherty limestone there is an abundance of Halysites catenularia, 



